An energy storage system (ESS) installed in a power plant driving a large-scale power network and a building having large power consumption may be generally configured to include a battery rack constituted by multiple battery modules, and consequently, numerous batteries may be collected and installed in a special space such as an air-conditioning building or container. In this case, a battery management system (BMS) is installed in the battery module and the battery rack for monitoring and controlling control targets including voltage, current, a temperature, a breaker, and the like.
Meanwhile, a power conversion system (PCS) installed in the energy storage system controls power supplied from the outside and power supplied from the battery rack to the outside to control charging/discharging of the battery rack and the energy management system (EMS) connected with the power conversion system controls an output of the power conversion system based on monitoring and control results of the battery management system.
That is, the energy storage system monitors and controls the battery rack through the battery management system in real time in order to enhance power efficiency of the battery rack and diagnose and prevent an obstacle which may occur in a high-output environment and controls the output of the power conversion system through the energy management system based on the monitored and controlled battery rack to control charging/discharging the battery rack.
As a result, it is important that communication using a signal is stably performed among the battery rack, the battery management system, the energy management system, and the power conversion system in the energy storage system and to this end, a countermeasure for conduction noise which is induced into the energy storage system to cause a communication failure and malfunction is required.
A transfer mode of the conduction noise includes two modes of a differential mode and a common mode and a noise countermeasure depending on a difference varies. In particular, since common mode noise induced through the common mode is generated by an imbalance of impedance of a wiring system, and the like and becomes remarkable at a higher frequency and transferred to a ground surface, and the like to return while forming a large loop, the common mode noise causes various communication failures even to a far-off electronic apparatus, and as a result, a countermeasure for the common mode noise becomes important.
Occurrence frequencies of the communication failure and the malfunction caused due to the common mode noise induced to the energy storage system are reduced as the insulation performance of the battery rack is excellent, and as a result, development of a common mode noise simulator for evaluating the insulation performance of the battery rack depending on the common mode noise is required.
Therefore, the present inventor has invented a common mode noise simulator which removes a high-frequency component by controlling impedance of an inductor, a capacitor, and a resistor and evaluates insulation performance of a battery by measuring leakage current of the battery depending on amplitude-modulated common mode noise.